With the advent of the deregulation of the telephone system in the United States, many conceptual changes have been required and are yet to be required in both telephone equipment and services, not the least of which is the identity of the party responsible for the repair and maintenance between equipment owned by subscriber (subscriber premise equipment) and telephone company-owned telephone outside equipment. The telephone subscriber, for instance, may now own his own telephone, premise wiring, PABX's, and other associated equipment, the maintenance of which is the sole responsibility of the premise owner.
Recent rulings by the FCC require that a device (network interface device) be installed on the premises of each subscriber that will permit testing of the integrity of that part of the subscriber loop owned by the telephone company. The rationale behind this rule is to provide a means that a subscriber may use to avoid a telephone service charge arising out of a subscriber complaint regarding faulty telephone service in those instances where the faulty service is in that portion of the subscriber loop belonging to the telephone company. By use of the invention shown in U.S. Pat. Nos. 4,488,008 and/or 4,741,032, the contents of which are incorporated herein by reference, either a subscriber and/or a telephone service person may unplug a previously connected jack and plug located in a network interface device, insert another plug connected to an operating telephone and if a call can be made using such an arrangement or dial tone heard, that portion of the subscriber loop owned by the telephone company is without fault and thus the fault must be in the premise wiring or equipment of the owner. The telephone subscriber may perform this testing function for himself and thus avoid a service call charge for trouble that is within that part of the subscriber loop owned by the subscriber and for which the subscriber is responsible.
In most cases, the network interface devices described by the above-identified United States Patents are disposed on the outside of a customer's premise, or they may be disposed in a common area of a multi-family dwelling unit such as an apartment house. Because of this public or semi-public location, they may be subject to abuse. Unauthorized individuals need only to access the interior of the network interface device, remove the plug of the network interface device from its jack, insert a plug connected to a telephone handset, as if a test of the telephone loop owned by the telephone company were to be performed, and make a telephone call, either local or toll, the charge for such call being lodged against the customer without his permission, knowledge, or blessing. It is in the context of this problem where the present invention is most useful.